Lithium rechargeable battery

ABSTRACT

A lithium rechargeable battery includes an electrode assembly having a first electrode, a second electrode, and a separator interposed between them, a can having an opening to contain the electrode assembly, and a cap plate coupled to the top of the can. A side of the can is asymmetrical with respect to another side thereof about at least one of a long axis, short axis, and central point of its cross section. The lithium rechargeable battery has a predetermined space formed between the can and the electrode assembly for improved electrolyte injection and increased manufacturing efficiency and power storage capacity of the battery.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2004-0078187, filed on Oct. 1, 2004, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lithium rechargeable battery that hasan internal space formed between a can and an electrode assembly toimprove electrolyte injection.

2. Description of the Prior Art

In general, a rechargeable battery may be charged and discharged, incontrast to a nonrechargeable battery which is not rechargeable, and canbe made in a compact size with a large power storage capacity. Typicalexamples of rechargeable batteries include nickel metal hydrogen (Ni-MH)batteries, lithium (Li) batteries, and lithium ion batteries. Recentlydeveloped lithium rechargeable batteries are widely used in cutting-edgeelectronic devices such as cellular phones and laptop computers.

Rechargeable lithium batteries are classified into lithium ion batteriesthat use a liquid electrolyte and lithium polymer batteries that use apolymer electrolyte. Rechargeable batteries may also be classified intocylindrical batteries that use a cylindrical aluminum can, rectangularbox batteries that use a rectangular box-shaped aluminum can, andpouch-type batteries that are contained in a plate-shaped pouch case.

A rechargeable battery generally comprises a can, an electrode assemblycontained in the can, and a cap assembly that is coupled to the topopening of the can. The electrode assembly is formed by winding a firstelectrode and a second electrode together with a separator interposedbetween them into a jelly roll. The electrode assembly is placed intothe can, the top opening of which is then sealed by the cap assembly.

FIG. 1 is a top view of a conventional rectangular box type rechargeablebattery with angled corners and FIG. 2 is a top view of a rectangularbox type rechargeable battery with rounded corners.

Referring to FIG. 1, a can 10 generally has angled corners, arectangular box-shaped space, and an electrode assembly 12 containedtherein. However, the corners of the rectangular box type rechargeablebattery shown in FIG. 1 are angled and do not accurately correspond tothe corners of the electrode assembly 12, which are rounded. As aresult, the can 10 has an unnecessary void that is not occupied by theelectrode assembly 12. This makes it difficult to maximize the batterycapacity and degrades the aesthetic appearance. In order to solve thisproblem, a rectangular box type rechargeable battery that has a can 20with rounded or curved corners as shown in FIG. 2 have recently beenused.

Referring to FIG. 2, the can 20 generally has curved corners, arectangular box-shaped space, and an electrode assembly 22 containedtherein together with an electrolyte (not shown). The curved corners ofthe can 20 accurately correspond to the curved portions of the jellyroll-shaped electrode assembly 22. As a result, unnecessary space is notcreated in the sides of the can 20.

However, since there is no space between the electrode assembly 22 andthe can 20 in the rechargeable battery with curved corners as shown inFIG. 2, it takes a long time to inject an electrolyte and theproductivity of the battery deteriorates. Furthermore, the lack of spacebetween the can 20 and the electrode assembly 22 makes it difficult touniformly inject the electrolyte into the electrode assembly 22. Thisdecreases the battery's power storage capacity.

SUMMARY OF THE INVENTION

The present invention provides a lithium rechargeable battery that hasan internal space formed between a can and an electrode assembly forimproved electrolyte injection.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

The present invention discloses a lithium rechargeable batterycomprising an electrode assembly including a first electrode, a secondelectrode, and a separator interposed between them. The battery furthercomprises a can having an opening to hold the electrode assembly and acap plate that is coupled with the top of the can, wherein a side of thecan is asymmetrical to the other side thereof about at least one of thelong axis, short axis, and central point of the cross section thereof.

The present invention also discloses a lithium rechargeable batterycomprising an electrode assembly including a first electrode, a secondelectrode, and a separator interposed between them. The battery furthercomprises a can having an opening to hold the electrode assembly and acap plate that is coupled with the top of the can, wherein a side of theelectrode assembly is asymmetrical to the other side thereof about atleast one of the long axis, short axis, and central point of the crosssection thereof.

The present invention also discloses a lithium rechargeable batterycomprising an electrode assembly including a first electrode, a secondelectrode, and a separator interposed between them. The battery furthercomprises a can having an opening to hold the electrode assembly and acap plate that is coupled with the top of the can, wherein the spacingbetween the can and the outer periphery of the electrode assembly on thecross section of the can and the electrode assembly varies about atleast one of the long axis, short axis, and central point of the crosssection.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a top view of a conventional rectangular box-type rechargeablebattery with angled corners.

FIG. 2 is a top view of a conventional rectangular box-type rechargeablebattery with rounded corners.

FIG. 3 is an exploded perspective view of a lithium rechargeable batteryaccording to a first embodiment of the present invention.

FIG. 4 is a top view of a lithium rechargeable battery according to afirst embodiment of the present invention.

FIG. 5 is a top view of a lithium rechargeable battery according to asecond embodiment of the present invention.

FIG. 6 is a top view of a lithium rechargeable battery according to athird embodiment of the present invention.

FIG. 7 is a top view of a lithium rechargeable battery according to afourth embodiment of the present invention.

FIG. 8 is a top view of a lithium rechargeable battery according to afifth embodiment of the present invention.

FIG. 9 is a top view of a lithium rechargeable battery according to asixth embodiment of the present invention.

FIG. 10 is a top view of a lithium rechargeable battery according to aseventh embodiment of the present invention.

FIG. 11 is a top view of a lithium rechargeable battery according to aneighth embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The lithium rechargeable battery of the present invention has apredetermined space formed between the can and the electrode assemblyfor improved electrolyte injection, manufacturing efficiency, and powerstorage capacity of the battery. This avoids a drop in productivitycaused by prolonged electrolyte injection time. Furthermore, asufficient amount of the electrolyte is easily injected through thespace formed between the can and the electrode assembly and isdistributed between the electrodes in a uniform manner.

FIG. 3 is an exploded perspective view of a lithium rechargeable batteryaccording to a first embodiment of the present invention. FIG. 4 is atop view of the lithium rechargeable battery according to a firstembodiment of the present invention.

Referring to FIG. 3, the lithium rechargeable battery 30 includes a can31, an electrode assembly 32 contained in the can 31, and a cap assembly40 that is coupled with the top opening of the can 31.

One side of the can 31 and another side of the can 31 are asymmetricalto each other about at least one of the long axis, the short axis, andthe central point of the cross section of the can 31. The cross sectionof the can 31 has four corner portions and at least one of the cornerportions is curved. In addition, one of the corner portions of the canis curved with a curvature that is different from that of another. Asshown in FIG. 3, a first corner portion 34 a is asymmetrical to secondcorner portion 34 b and has a curvature smaller than that of the latter.Consequently, the first corner portion 34 a does not accuratelycorrespond to the curved portion 33 of the electrode assembly 32 and aspace 31 a is formed between the first corner portion 34 a and thecurved portion 33 of the electrode assembly 32. Similarly, a space 31 bmay be formed between the second corner portion 34 b and the curvedportion of the electrode assembly 32.

The can 31 may comprise, but is not limited to iron, aluminum, or analuminum alloy. When the can 31 is made of aluminum or an aluminumalloy, the battery may be lightweight due to the light weight ofaluminum and it may not corrode even when used for a long time underhigh voltage.

The electrode assembly 32 is formed by winding a first electrode 35 anda second electrode 37 with a separator 36 interposed between them. Thefirst electrode 35 is coupled with a cap plate 60 via a first electrodetab 38 and the second electrode 37 is coupled with a second electrodeterminal 50 formed on the cap plate 60 via a second electrode tab 39.The first electrode 35 or second electrode 37 may act as a positiveelectrode or a negative electrode.

The cap assembly 40 is coupled with the top opening of the can 31 toseal it while being insulated from the electrode assembly 32 by aseparate insulation case 90. The cap assembly 40 has a planar cap plate60 that has a size and a shape corresponding to the top opening of thecan 31. The cap plate 60 has a terminal through-hole 61 that is formedat its center to allow the second electrode terminal 50 to pass through.

The second electrode terminal 50 extends through the center of the capplate 60 and has a tube-shaped gasket 35 that is positioned on itsexterior to insulate the second electrode terminal 50 from the cap plate60. An insulation plate 70 is positioned on the lower surface of the capplate 60 near the terminal through-hole 61 of the cap plate 60. Aterminal plate 80 is positioned on the lower surface of the insulationplate 70 while being coupled with the first electrode terminal 35.

The cap plate 60 may have a safety vent (not shown) that is formedthereon to discharge gas when the internal pressure rises and reaches apredetermined level. The cap plate 60 also has an electrolyte injectionhole 62 that is formed on its side to provide a passage along which anelectrolyte can be injected into the can 31. The electrolyte injectionhole 62 is sealed by an electrolyte injection ball 63. The cap plate 60may have a protective circuit module (not shown) that is positioned onits upper side to control the charging and discharging of the battery.The protective circuit module may be installed using a resin mold.

Referring to FIG. 4, a pair of second corner portions 34 b of the can 31that are positioned on one side of the long axis of the cross section ofthe can 31 have a curvature that is different from that of a pair offirst corner portions 34 a that are positioned on the other sidethereof. As a result, predetermined spaces 31 a and 31 b may be formedbetween the curved portion 33 of the electrode assembly 32 and the firstcorner portions 34 a. For example, the first corner portions 34 a mayhave a curvature that is smaller than that of the second corner portions34 b and predetermined spaces 31 a and 31 b may be formed between thefirst corner portions 34 a and the curved portion 33 of the electrodeassembly 32.

With spaces 31 and 31 b formed in this manner, an electrolyte (notshown) can be rapidly injected into the can 31. Furthermore, asufficient amount of electrolyte may easily be injected into theelectrode assembly 32 to be distributed between the electrodes in auniform manner, thus increasing the battery's power storage capacity.

FIG. 5 is a top view of a lithium rechargeable battery according to asecond embodiment of the present invention.

Referring to FIG. 5, a pair of second corner portions 34 b of the can 31that are positioned on one side of the short axis of the can 31 have acurvature that is different from a pair of first corner portions 34 athat are positioned on the other side thereof. The first corner portions34 a have a curvature that is smaller than the curvatures of the secondcorner portions 34 b. Thus predetermined spaces 31 a and 31 c may beformed between the first corner portions 34 a and the curved portion 33of the electrode assembly 32. Since the electrolyte is injected throughthe electrolyte injection hole 62, the first corner portions 34 a arepreferably positioned on a short edge on which the electrolyte injectionhole 62 of the can 31 is formed. If the internal space of the can 31formed by the first corner portions 34 a are formed on a short edgeopposite to the electrolyte injection hole 62, the electrolyte injectiontime may not be reduced as desired.

FIG. 6 is a top view of a lithium rechargeable battery according to athird embodiment of the present invention.

Referring to FIG. 6, a pair of corner portions of the can 31 that arepositioned on a side of the central point of the cross section of thecan 31 are asymmetrical to each other, while the other pair of cornerportions positioned on the other side thereof are symmetrical to eachother. A first corner portion 34 a of the pair of corner portions whichare asymmetrical to each other has a curvature that is smaller than thatof the second corner portion 34 b and is preferably positioned on ashort edge on which the electrolyte injection hole 62 of the can 31 isformed. Since the electrolyte is injected through the electrolyteinjection hole 62, the electrolyte injection time may not be reduced asdesired if the internal space of the can 31 formed by the corner portion34 a is formed on a short edge opposite to the electrolyte injectionhole 62.

FIG. 7 is a top view of a lithium rechargeable battery according to afourth embodiment of the present invention. FIG. 8 is a top view of alithium rechargeable battery according to a fifth embodiment of thepresent invention.

Referring to FIG. 7, a pair of first corner portions 34 a of the can 31that are positioned diagonally from the central point of the crosssection of the can 31 are symmetrical to each other and have a curvaturethat is smaller than that of the pair of second corner portions 34 b.Thus, predetermined spaces 31 a and 31 d may be formed between the firstcorner portions 34 a and the curved portion 33 of the electrode assembly32. Alternatively, three first corner portions 34 a may form apredetermined space with the curved portion 33 of the electrode assembly32, as shown in FIG. 8. In that case, predetermined spaces 31 a, 31 b,and 31 c may be formed between the first corner portions 34 a and thecurved portion 33 of the electrode assembly 32.

In addition, a pair of corner portions that are positioned diagonallyabout a central point may be right-angled, while the other pair ofcorner portions that are positioned diagonally about central point maybe curved.

FIG. 9 is a top view of a lithium rechargeable battery according to asixth embodiment of the present invention. FIG. 10 is a top view of alithium rechargeable battery according to a seventh embodiment of thepresent invention. FIG. 11 is a top view of a lithium rechargeablebattery according to an eighth embodiment of the present invention.

Referring to FIG. 9 and FIG. 10, the can 31 has curved second cornerportions 34 b and right-angled first corner portions 34 a that arepositioned on the long or short edge thereof. Thus, predetermined spaces31 e and 31 f may be formed between the right-angled first cornerportions 34 a and the curved portion 33 of the electrode assembly 32 asshown in FIG. 9, and predetermined spaces 31 e and 31 g may be formedbetween the right-angled first corner portions 34 a and the curvedportion 33 of the electrode assembly 32 as shown in FIG. 10.

Referring to FIG. 11, the can 31 may have a pair of curved second cornerportions 34 b and a pair of right-angled first corner portions 34 a. Thecurved second corner portions 34 b are positioned diagonally from thecentral point of the cross section of the can 31. The right-angled firstcorner portions 34 a are positioned diagonally from the central point ofthe cross section of the can 31. Thus, predetermined spaces 31 e and 31h may be formed between the right-angled first corner portions 34 a andthe curved portion 33 of the electrode assembly 32 as shown in FIG. 9

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A battery, comprising: an electrode assembly including a firstelectrode, a second electrode, and a separator interposed between them;a can having an opening to contain the electrode assembly; and a capplate coupled to the can, wherein a side of the can is asymmetrical withrespect to another side of the can about at least one of a long axis,short axis, and central point of its cross section.
 2. The battery ofclaim 1, wherein the can has four corner portions in its cross section,and wherein at least one of the corner portions is curved.
 3. Thebattery of claim 2, wherein one side of the can has a differentcurvature than another side thereof.
 4. The battery of claim 2, whereinone side of the can and another side thereof have a curved cornerportion and a right-angled corner portion, respectively.
 5. The batteryof claim 2, wherein corner portions that are positioned on a side of thelong axis have a curvature that is different from corner portions thatare positioned on another side of the long axis.
 6. The battery of claim2, wherein corner portions that are positioned on a side of the shortaxis have a curvature that is different from corner portions that arepositioned on another side of the short axis.
 7. The battery of claim 2,wherein a first pair of corner portions that are positioned on two sidesabout the central point are right-angled, and wherein a second pair ofcorner portions that are positioned on two sides about the central pointare curved with a predetermined curvature.
 8. The battery of claim 2,wherein a first pair of corner portions that are positioned on two sidesabout the central point are asymmetrical to each other, and wherein asecond pair of corner portions that are positioned on two sides aboutthe central point are symmetrical to each other.
 9. A battery,comprising: an electrode assembly having a first electrode, a secondelectrode, and a separator interposed between them; a can having anopening to contain the electrode assembly; and a cap plate coupled tothe can, wherein a side of the electrode assembly is asymmetrical withrespect to another side thereof about at least one of a long axis, shortaxis, and central point of its cross section.
 10. The battery of claim9, wherein one side of the electrode assembly has a curvature differentfrom that of another side thereof.
 11. A battery, comprising: anelectrode assembly having a first electrode and second electrode, and aseparator interposed between them; a can having an opening to containthe electrode assembly; and a cap plate coupled to the can, wherein thespacing between the can and an outer periphery of the electrode assemblyon a cross section of the can and the electrode assembly varies about atleast one of a long axis, short axis, and central point of the crosssection.